Process of separating carotene fractions and tocopherol-sterol fractions from green plant materials



awn a. 31, 1950 PROCESS OI SIPARA'HNG CARO'IINE FRACTIONS AND TOOOPHEBOL-STEROL FRACTIONS FROM GREEN PLANT MA- TRIALS Monroe 8. Wall, Oreland, Pa, alsignor to the United States of America as represented by the Secretary of Agriculture No Drawing. Application July 29, 1947, Serial No. 104,549

1. Claims. (CL 167-81) (Granted under the act of March 8, 1883, as amended April 30, 1928; 370 0. G. 757) This application is made under the act of March 3, 1883, as amended by the act of April 1928, and the invention herein described, if patented, may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment to me of any royalty thereon.

This invention relates to the treatment of plant materials, particularly green leaves, and has among its objects the provision of methods of treating said plant materialsto recover carotene, xanthophyll, tocopherol, and sterols as fractional concentrates of molecular distillation.

The preparation of carotene and xanthophyll from green leaves has been studied'extensively.

are described, for example, by Hickman Chemical Reviews, 34, 51 (1944). This method is limited to liquids of low vapor pressure and its industrial application has been restricted almost exclusively to the treatment of fish liver or vegetable oils.

As a result of the molecular distillation of the oil stituents of green leaves.

All the methods heretofore utilized involve extraction with solvents, such as hexane or acetone, followed by various saponification or adsorption treatments used singly or in combination. These procedures often require numerous steps and frequently result in the loss of many valuable constituents of the material treated. Practically no information on the recovery of tocopherols or sterols from green leaves appears to be available.

Saponification of leaf meal extracts sometimes causes partial destruction of the more unstable compounds present. On the other hand, distillation of the leaf meal extract without previous saponification does not yield satisfactory results due to persistent and violent foaming and splashing which occur during the distillation and also because some of the constituents of the leaf extract, being relatively insoluble in the oil carrier, tend to clog the pumping and distributing systems of the still.

I have found that the carotene, tocopherol, and sterols of green leaves can be separated into fractions rich in carotene and in .tocopherol and sterols by mixing a solut on of a low boiling organic solvent containing these constituents, with a high boiling oil, removing the low boiling organic solvent and then subjecting the resulting oil solution of the constituents to molecular distillation. Molecular distillation may be defined as a distillation process conducted at pressures of about from 1X10- to 100X10- centimeter of mercury and under such conditions that the distance between the evaporating and the condensing surfaces is relatively short. The procedures and equipment utilized in molecular distillation The first, which will be called Process A, involves extracting leaf meal with a low boiling organic solvent such as hexane or acetone, saponifying the extract, for example, by the procedure described in Patent No. 2,394,278, removing the saponifled material, mixing the remaining organic solvent solution of unsaponifiable material with a high boiling oil such as cottonseed, soybean, peanut, or similar vegetable oil, removing the organic solvent from this mixture, and then subjecting the resulting oil solution which contains the aforementioned constituents, to molecular' distillation. As a result of this procedure carotene, xanthophyll, tocopherol, and sterol can be recovered as fraction concentrates in high yields.

. The distillation can also be conducted in the presence of other high boiling oils, such as a mineral oil, although vegetable oils are preferred in the production of edible concentrates.

Phytol, which is a product of the saponification of chlorophyll, is also recovered as a fraction concentrate in high yield, it being obtained in the first distillate.

The second process, which will be called Process B, involves extracting the plant material, principally green leaves, with a low boiling organic solvent such as a hydrocarbon like pentane, hexane, heptane, or a chlorinated hydrocarbon like chloroform, or with ether or a similar organic fat solvent. The leaf extract is not saponifled as in Process A, but instead, the unsaponified leaf extract is dissolved in a low boiling oxygen-containing organic solvent, such as a lower aliphatic ketone like acetone or methyl-ethyl ketone, or in a lower aliphatic alcohol like methyl, ethyl, or

3 p pyl alcohol. The resulting solution is mainpresent, would be found in this distillation range. tained at a temperature not substantially in ex- The highest concentrations of tocopherol and cos of room temperature (25 0.), or preferably sterol are found in the 140 and 160 and 180 cooled to about 4 to 5 C., for a length of time fractions. Depending on the source of leaf meal, suflicient to cause separation of the insoluble 5 tocopherol concentrations of to percent and components, as evidenced by the formation of a sierol from 20 to percent are secured. voluminous precipitate which is readily removed The distillate at 200 to 220 C. contains 1 to by filtration. The filtrate so obtained contains 2 percent carotene largely in cottonseed oil-which substantially all the carotene, xanthophyll, tobegins to distill at this temperature. The residcopherol, and sterols present in the original ex- 10 ual oil contains carotene, sterol, and tocopherol tract dissolved in the oxygen-containing organic in low concentrations and along with considersolvent. The filtrate is then mixed with a high able quantities of unidentified products. boiling oil, as in Process A, and the solvent is re- Table I gives the details of a typical distillation moved. The residual oil solution can then be of the unsaponiflables from 25 pounds rhubarb fractionated by molecular distillation in a manner 15 leaf meal (74 grams in 300 grams cottonseed 011).

Table I Carotene Tooopbotol Stem] Product Appearance Weight, g.

' Per Cent Per Cent 2 Per Cent Oil soln. of unsaponinsbles Red on 374. 0 0.38 1.4 1. e 1. e 1. 0 7. 0 Distillate 100 C- Viscous yellow oil 12.0 0.0 0.0 0.10 0. 11 0.05 0.06 Distillate 120 0.. Semi solid yellow".-- 7.4 0.0 0. 0 5.8 0.50 6. 0 0. 44 Distillate 140 0.. Orange solld..-. 5. 8 0.0 0. 0 2. 4 1.30 25. 0 1.50 Distillate 160 0 do 7. 2 0.0 0.0 19.4 1.40 29. 4 2.1

)istillate 180 C .do 7,0 Trace Trace 16.0 1.10 18.0 1.26 Distillate 200221? 0 Red oil 40.0 1.0 0. 40 l. 0 0.40 1.2 0.48 Residue- 9.o a r I 278 0. 13 0.35 0. 2 0. 56 0.2 0. 50

analogous to that used in the distillation of the From the above table it can be seen that in unsaponiflable portion of leaf extractinProcess A. the most potent fractions carotene is concen- As will be observed, Process B does not utilize trated about threefold, with a total recovery any saponiflcation procedure and consequently about 50 percent, tocopherol 10 to 12 fold with no phytol is recovered. The carotene, xanthoa total recovery close to 90 percent, sterol 10 to phyll, tocopherol, and sterols, however, are re- 15 foldwith a total recovery about 90 percent. covered in high yields. If phytol is required, the With centrifugal stills that are available, the extraction of the leaf meal with the low boiling carotene recovery can be raised to 90 percent or organic solvent, the solution of the resulting exbetter.

tract with the low boiling oxygen-containing or- Both the distilled and residual carotene fracganic solvent, followed by saponiilcation and distions are free from odor and bland in taste in tillation in the usual manner is necessary. contrast to carotene concentrates prepared in The following examples are illustrative of the the conventional manner. The distilled carotene invention. can be used for edible purposes. Its concentramMPLE I (PROCESS A) tion 1 to 2 percent approaches the maximum solubility of carotene in oil at room temperature.

Twenty-five pounds of leaf meals are extracted The residual oil contains 2000 to 30001. U. A per with 5 gallons of acetone, the solvent concengram, the same concentration as commercial trated to about 2 gallons and the solution saponivitamin A fish liver oils used for poultry feeding fled with barium hydroxide, using the procedure oils. Both the distilled and residual oils contain described by Petering et al. Ind. 81 Eng. Chem. 32, xanthophyll with concentrations and recovery 140, 1940. The saponiilcation products are sepsimilar to that given for carotene. arated, and the remaining solution of unsaponiflables is mixed with cottonseed oil and all the sol- EXAMPLE n (PROCESS vent removed, preferably under conditions of n y pounds of broccoli leaf meal were exmild heat and in vacuo. In most cases one-third tracted with 5 llons hexan The hexane was to one-half pound of cottonseed n is a t m concentrated to a volume of 1 quart under vacuo vehicle for the unsaponiflable products obtained 0 and d heat O 88110118 ne we from 20 to 25 pounds leaf meal. added with vigorous stirring and the solution al- The oil solution of unsaponifiables is now ready lowed to stand t 4 C. v t. The solution for molecular distillation. A cyclic molecular W88 filtered-8 ous Solid Sludge was easily still is used and the oil is circulated in the still removed- The p p te was t Was ed. The and kept at a temperature of 50 to C. until 05 e ove y of the desired constituents was almost it is degassed. Distillation is then started at quantitativepressure of 5 t 20 microns (5x104 to 20 1o0 The original hexane extract contained 385 cm. Hg). Fractions are taken at s s s l ds. Aft r t a to pr ip n. 100, 180, and 200 to 220 c. The 100 fraction e filtrate c n ined 187 grains solids; so that is chieily, phytol (derived from chlorophyll) but 7 approximately f e Sol s we e ve y may contain small quantities of tocopherol and this treatment The p pitate consisted larg y sterols. The 120, 140, and 180 fractions of phospholipids and unknown products, and concontain as identifiable constituents tocopherol tained 30 percent unsaponifiable material. and sterols. The nature of. the unidentified prod- The acetone filtrate was mixed with 1 pound ucts is largely unknown-although vitamin K, if 76 cottonseed oil and the solvent evaporated. The

ruidual oil solution was free flowing and contained no insoluble matter at room temperature. The oil solution was then molecularly distilled as described previously in Example 1. However,

- 6 4. The process of claim 2 wherein the high boiling oil is a vegetable oil.

5. The process of claim 2 wherein the big boiling oil is a mineral oil.

6. A process of separating fractions rich in car-' otene and in tocopherol and sterols from green plant materials comprising extracting leaf meal containing carotene, tocopherol and sterols with -a low boiling organic fat solvent, dissolving the resulting extract in a low boiling oxygen-containing organic solvent selected from the group consisting of lower aliphatic ketones and lower aliphatic alcohols, maintaining the solution so Table II Osrotcnc Tocophcrol Stem! Product Appearance W l hl- Psi-Cent Pei-Cent 2 Pei-Cent a on m. m mma after Green oil... 001 0.50 3.4 0.01 3.7 1.40 0.0

' Yellowviscousoil 3.0 0.0 0.0 3.1 0.11 0.7 0.21

Orange 0.2 0.0 0.0 0.: 0.86 am 2.43 0.1 0.0 0.0 12.0 1.22 30.2 202 d 11.3 Trace Trace 0.0 0.00 20.0 220 100. 1. 2s 1. 0.12 0. 42 1.12 1.12 500.00 0.18 .90 Trace Trace From the data of Table II it can be seen that 60 percent of the carotene and over 90, percent of the tocopherol and sterols are recovered. In the most potent fractions carotene is concentrated twofold, tocopherol about 20 times and sterol 20 times. Therefore the concentration of the potent fractions is similar to that obtained with the saponification procedure.

A further purification of the toccpherol-sterol fractions is easily carried out by taking the material up in boiling ethanol and after cooling, filtering the precipitate which is largely sterols. One such treatment is sufllcient to double the potency of tocopherol and sterol.

Having thus described my invention, I claim:

1. A process comprising mixing a solutionof a low boiling organic solvent containing carotene, ,tocopherol, and sterols with a high boiling oil, removing the low boiling organic solvent from the resulting mixture, and subjecting the residual oil solution containing the carotene, tocopherol, and sterols to molecular distillation to separate. as distillation fractions, a substantially carotenefree tocopherol-sterois fraction at a temperature of about from 120 to 180 C. and a fraction rich in carotene at a temperature exceeding about 180 C.

2. A process of separating fractions rich in carotene and in tocopherol and sterols from green plant materials comprising extracting leaf meal containing carotene, tocopherol, and sterols with a low boiling organic solvent, saponifying the re-' sulting extract, separating the sponiiled material from the unsaponiflable material, mixing the resulating low boiling organic solvent solution of the unsaponiflable material with a high boiling oil, removing the low-boiling organic solvent from the resulting mixture, and subjecting the residual oil solution containing the carotene, tocopherol, and sterols to molecular distillation to separate, as distillation fractions, a substantially carotene-free tocopherol-sterols fraction at a temperature of about from 120 to 180 C. and a fraction rich in carotene at a temperature exceeding about 180 C.

3. The process of claim 2 wherein the low boiling organic solvent is acetcne.

formed at a temperature not substantially in ex- ,cess of 25 C. for a length of time suflicient to cause the separating out of insoluble components, removing the insoluble components, mixing the residual solution with a high boiling oil, removing the low boiling organic solvents from the resulting mixture, and subjecting the residual oil solution containing the carotene, tocopherol, and sterols to molecular distillation to separate, as distillation fractions, a substantially carotenefree tocopherol-sterols fraction at a temperature of about from 120 to 180 C. and a fraction rich in carotene at a temperature exceeding about 180 C..

7. The. process of claim 6 whereinthe low boiling organic fat solvent is hexane.

8. The process of claim 6 wherein the temperature at which the solution of the extract and the low boiling oxygen-containing organic solvent is maintained until separation of insoluble components occurs, is about from 4 C. to 5 C.

9. The process of claim 6 wherein the low boiling oxygen-containing organic solvent is a lower aliphatic ketone.

10. The process of claim 6 wherein the low boiling oxygen-containing organic solvent is acetone.

MONROE E. WALL.

REFERENCES CITED The following references are of record in the file of this patent:

' UNITED STATES PATENTS -Number Name Date 2,098,254 Mattill Nov. 9, 1937 2,131,394 Test Sept. 27, 1938 2,146,894 Hickman Feb. 14, 1939 2,150,684 Hickman Mar. 14, 1939 2,180,356 Hickman Nov. 21, 1939 2,207,385 Smith July 9, 1940 2,256,392 Hickman Sept. 16, 1941 2,327,766 Cawley Aug, 24, 1943 2,383,561 Petering Aug. 28, 1945 2,394,278 Wall Feb. 5, 1946 2,432,181 Trent Dec. 9, 1947 (References 011 following page) 7 0mm) STATES PATENTS Number Name Date 2,482,635 Pe'tering Sept. 20, 1949 FOREIGN PATENTS Number Country Date 565,095 Great Britain Oct. 24, 1944 5 120, Sept. 1937, p es 635 to 640. 

1. A PROCESS COMPRISING MIXING A SOLUTION OF A LOW BOILING ORGANIC SOLVENT CONTAINING CAROTENE, TOCOPHEROL, AND STEROLS WITH A HIGH BOILING OIL, REMOVING THE LOW BOILING ORGANIC SOLVENT FROM THE RESULTING MIXTURE, AND SUBJECTING THE RESIDUAL OIL SOLUTION CONTAINING THE CAROTENE, TOCOPHEROL, AND STEROLS TO MOLECULAR DISTILLATION TO SEPARATE, AS DISTILLATION FRACTIONS, A SUBSTANTIALLY CAROTENEFREE TOCOPHEROL-STEROLS FRACTION AT A TEMPERTURE OF ABOUT FROM 120* TO 180C. AND A FRACTION RICH IN CAROTENE AT A TEMPERATURE EXCEEDING ABOUT 180*C. 